A method closely related to the classical augmented-plane-wave (APW) method is developed which treats in a nearly exact way the Hartree-Fock exchange in the case of crystals having deeply bound and filled valence bands. Band-structure calculations have been performed for solid neon and argon. The main conclusions of Lipari and Fowler for argon are confirmed: a too large gap which proves the influence of correlation in these insulators, large valence bands, and change in the shift between conduction bands without significant modification of their internal structure. Yet, we note that we found a smaller separation between $s$ and $d$ bands than Lipari and Fowler. The value of the Hartree-Fock energy gap is physically related to the experimental one in terms of the correlation energies involved in a transition from a localized valence state to an extended conduction state. Using atomic correlation values for the valence state and previous results for the polarization in solid rare gases, a good qualitative agreement is found.

• Received 21 June 1971

DOI:https://doi.org/10.1103/PhysRevB.5.641